1. Field of the Invention
The present invention relates to flexible printed circuits, and more particularly to a method of assembly electronic components to a flexible printed circuit board.
2. Description of the Background
It is recognized in the art that a flexible printed circuit is a series of serigraphed conductors using conductor paste on a thin sheet of flexible backing usually made of a film of plastic material, such as, for example, polystyrene, polyamide, or ethylene resin.
The assembly of the electronic components on these flexible printed circuits presents numerous difficulties; the welding methods traditionally used on rigid printed circuits cannot be used with flexible printed circuits in that the conductor paste, because of its very nature and composition, cannot be welded to the connections of the components.
At present, conductor bonding agents are used which, once they reach their polymerization temperature, are able to guarantee a reliable and strong connection. However, this assembly technique requires time and its costs are high.
In addition, the resulting adherence of the conductor to the supporting flexible film is rather weak and precarious, so it is easy for an accidental break to occur between the parts, especially if the film is bent near the connection point of a component.
In order to avoid this risk and to increase the reliability of assembly, the electronic component and its connection could be encapsulated by covering them with a high bond rigid resin, but this would mean a further cycle in the oven with a consequent increase in time and production costs.